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Date: Sat, 22 Jun 1996 15:41:26 -0500 (CDT)
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From: Alex Nash <alex@zen.nash.org>
To: freebsd-hardware@freebsd.org
Subject: Mixing SIMMs of different speeds
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I'm wondering if I can mix 60 and 70ns SIMMs.  Everyone says don't,
but they don't say why.  I can understand not mixing SIMMs that will
be accessed simultaneously (like banks 1 and 2), but why shouldn't it
work when they are separated?  My motherboard's manual indicates 70ns
or faster will work, so why wouldn't a mixture?

So I add 2 70ns SIMMs to the motherboard that had 60s in banks 1 and
2, and (not too surprisingly) strange things happened.

I removed the 60s and ran with just the 70s, it seems to be working
great.

Now I'm starting to think, what if I ran with 70s in banks 1 & 2 and
60s in banks 3 & 4?  Since the motherboard runs with 70s ok, but the
60/70 mixture didn't work the first time, it must be able to determine
the access speed.  Is the motherboard using bank 1 to determine what
speed it should access memory with?  (This is a Tyan S1462 MB.)

Alex